db-derby-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Edson Carlos Ericksson Richter <edson.rich...@mgrinformatica.com.br>
Subject Re: Very slow
Date Wed, 01 Jun 2005 17:19:23 GMT
Thanks for fast response.

I think the reason Derby didn't used any index  is because since this 
table, for my tests purposes has only one record, I've not created any 
index at all.
I suspect that one record table will be in cache for a long time (since 
it's a comment making queries over this table in my code). At all, this 
one record is having "cost 13", so it's not the problem.

My problem appear be in the sub-select. Each sub-select make queries 
over a 33000 records table. I think I forgot to make a better index for 
it. After indexing, performance got better (not perfect, but it's usable 
- I think the large amout of log being generated is the reason for the 
little delay in responses). The cost for sub-select query dropped down 
from near 13000 to 19,85.

I other databases (like MaxDB and MS SQL, this table was kept in memory, 
because he is considered "small"). That's the reason I never made any 
indexing over it.

I'll try links sent at other mails, so I could discover if Tomcat 
integration has it's secrets too.

Thank you all for comments,

Edson Richter


Mime
View raw message